The present invention relates to a metering valve and more particularly to a valve assembly for controlling the flow of fluid independent of the pressure fluctuations at the input and the output of the assembly.
The need for an electro-fluid-flow valve for use in automobiles has been necessitated by various government regulations regarding pollution control and fuel economy. It has therefore become economical to use electronic devices for automotive engine control. Such electronic devices seek to control the flow of fuel to the engine as a function of an electrical signal. These devices seek to render the flow of fuel independent of pressure fluctuations at the input and the output of the metering valve assembly and completely dependent on the electrical signal to the fluid flow assembly.
Typical prior art devices sought to achieve control of fuel flow independent of the pressure fluctuations by measuring the flow of fuel and then developing and electrical signal which is an analog function of the fuel flow. The electrical signal is monitored by an electronic device which controls the opening of an electro-fluid-flow valve as a function of pressure drop measurements which were also converted to electrical signals and monitored by the same electronic device. This prior art technique requires two relatively expensive measurement transducers. It also requires the complicated electronics required to regulate the flow with reasonable accuracy.
Such typical prior art devices are relatively expensive in view of the need for hardward to measure both fluid flow and pressure. They also require compensating circuits in the electronics to regulate the flow accurately.